I'm not certain, but think when the knees are bone on bone, only a TKR will help get rid of the pain, and allow a lot more activity in the gym. The only things that can't be done are impact exercises - so no running, tennis, jump rope - but there is a whole lot that can be done - for strength and cardio.

I'm a 69 y/o male and had both knees replaced in 2022. I hired a trainer and strengthened my legs pre surgery, and then was fanatical about post op PT and exercises. I was a marathon runner before, but it was osteoarthritis that did in my knees.

So with that, I suggest finding a good ortho surgeon to discuss TKR. My recovery was phenomenal and I was back in the gym within two months. For cardio, I do intervals on a rowing machine at 80% of max HR. And I do spin classes and still work with a trainer on total body conditioning. I don't remember feeling this good physically.

As for a surgeon, my criteria in finding someone - mid 30s to mid 40s, good pedigree from college and/or residency and skilled with a robotic assistant. My guy did his residency at the Cleveland Clinic, was in his late 30s, and was skilled using the Stryker/Mako robotic assistant.

All the best to you friend. (And BTW, I have never heard of any type of injection or stem cell therapy that will revive a knee once the cartilage is gone. FWIW. Maybe one day, but I don't think it's possible today.)